I wish Time Machine did this (feature request/longing rant)

I wish Time Machine let the user preserve/lock certain snapshots for all eternity. Retrospect allows the user to do this. For instance, I could lock the 11/29/2008 snapshot for all time so that I can always go back to 11/29/2008, even if the snapshots from 11/30/2008 to 3/10/2010 all get automatically deleted to make space for 3/11/2010 to 5/15/2010.

The following work-around can be used to get my dream feature, but it hobbles the search function of Time Machine: Have two external drives. One is continuously plugged in and has the most recent snapshots (the oldest ones have been deleted). The other external drive only gets plugged in on rare occasions, those are the occasions that you want to save for eternity. Downsides: You cannot retroactively decide that you wish a certain snapshot was preserved, you have to make that decision the day of the snapshot. If your "special moments only" disk fills up, you are again in the situation of losing your oldest snapshot.

I have questions, too:
If I use SuperDuper to clone my Time Machine Backup drive to another drive, will everything work out nicely? For instance, will I be able to plug in the cloned drive, open Time Machine, and view that old snapshot and restore from it? I assume and dearly hope the answer is yes. If the answer is yes, you can do two nice things:

1. You can preserve a snapshot which is about to be deleted by cloning the whole time machine drive onto a new drive, and then only pushing a new backup to one of the drives. One of the drives won't be as up to date, but it will preserve the important old snapshot.

2. You can move to a bigger hard disc when needed. This will actually forestall the deletion of the oldest snapshot. This is also an absolutely imperative feature if Time Machine is expected to work for ever.

In conclusion: Time Machine, please be more like Retrospect. Your user interface and search feature leave Retrospect coughing in the dust, but you should go back and steal Retrospect's customizable snapshot preservation feature.

There is a way. Create the time machine back up. Then move it from the backup hard drive to another. It is kept for posterity, while new back ups are made.

Click to expand...

Ah, but this has the problem that it is not fully searchable by Time Machine. It also has the problem that it takes up extra space (or it might). Let me explain: My MacBook Pro currently contains 224 GB of data. Hypothetically, in two years when my backup drive becomes full and it deletes the oldest snapshot, this will might only free up 2 GB of stuff because the other 222 GB might be contained in more recent snapshots. Storing that snapshot for eternity with a "preserve snapshot" feature in Time Machine thus only takes up 2 GB extra. Storing it on a whole different drive takes up 224 GB. Big difference.

I could use Retrospect, which has this "preserve snapshot" feature, but I don't like the UI as much as Time Machine. And again, if I make a Retrospect backup and a Time Machine backup, then neither one has a full search library.

Maybe it's time to get outside the box and examine why you find yourself feeling the need to backup a specific date's files. Better organization might eliminate the supposed need for this. For my own workflows, both personal and work, I have a difficult time imagining myself in your situation. I'm trying to figure out what kind of trigger would make me want to retroactively decide to save a backup from months ago. Anything important to me is still being backed up today. Just a thought.

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